C# has LINQ. Implement Select and SelectMany extension methods for whatever you like, and you can use the LINQ syntax with your type just as easily as with IEnumerable. Foreach and async/await are baked in, that's true, but the LINQ syntax is easily extendable to new use cases.
What we have done, and what the mathematicians call Monads, we have identified these sets of operations, we call them standard query operators; we have a list of about 25 standard operators that you can apply to any data model.
